The data returned may change over time, but will be kept to characters between A-Z, a-z, 0-9, _ and - and a maximum length of 256 characters (currently it is much shorter).

It is safe to put in a URL (note: Length may become an issue in the future); insert into a database (although you should always use BIND columns); as an attribute or text section of XML (also HTML) (but not as a Tag name); store as a filename on disk; key/value in a Hash etc.

These tokens are hard to guess. That does not mean there is no overlaps. Using a hashing system such as MD5 or SHA-1 still means possibility of overlap. MD5 is a problem in signatures against large documents because you can change parts of the document without changing the meaning. But this system is only using MD5 to hide the secret and add unpredictability. So MD5 or SHA-1 - Jury is out.

Although the numbers are unpredictable there is alwas bruit force attacks. These need to be guarded against. A system should increase the time delay on requests as the attack increases. If you are using Apache this can be done with other modules, or integrated into your solution.

This module is written to replace embedded modules in applications such as CGI::Session, but also for non-standard modules you have to write yourself (e.g. Creating a unique URL for returning private data).

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